Lever-actuated switch



1956 A. ULRICH 2,761,040

LEVER-ACTUATED SWITCH Filed May 12, 1955 i INVENTOR ATTORNEYS UnitedStates Patent LEVER-ACTUATED SWITCH Alfred Ulrich, Rietheim, nearZurzach, Switzerland, as-

signor to Aktiengesellschatt Brown, Boveri & Cie, Baden, Switzerland, ajoint-stock company Application May 12, 1955, Serial No. 507,945 Claimspriority, application Switzerland May 17, 1954 '2 Claims. (Cl. 200-446)Lever switches for heavy currents are known, which are provided with twocurrent carrying switching points, said switching points being guided insuch manner that they will open and close one after the other with theoperating mechanism reversing its direction for each make and break.There also exist lever switches with one main and one auxiliaryswitching point where the auxiliary contact takes over the duty ofmaking and breaking the circuit; it is always the first to close and thelast to open the circuit. Another method, which employs lever switcheswith one main and one secondary switching point, specifies that the maincontact opens ahead of the secondary contact when breaking the circuitand that this sequence is reversed for the making of the circuit.Finally there is a method known which employs two current carrying powerswitches working in parallel which are guided in such manner that theswitching point which opens last will break, and the switching pointwhich opens first will make the circuit.

An object of the invention is to provide a lever switch with twoparallel and current carrying switching points, one of which will alwaysbe the last to be opened as well as the last to be closed. It is thebasic characteristic of the invention that the moveable contact of thatswitching point, which will always be the last to be active, is locatedon a bellcrank lever, said lever being subjected to a compressive forceand mounted to pivot at the end of a singlenrmed lever, saidsingle-armed lever carrying the moveable contact of the second switchingpoint, and that the free arm of said bellcrank lever is connected bymeans of a steering arm to another single-armed lever which in turn islinked to the first single-armed lever carrying the moveable contact ofthe second switching point and forming a knee joint with a drivingcrank, which turns always in the same direction, said knee joint beingin its stretched position when the switch is closed.

A practical example of the invention is presented in somewhatdiagrammatic form in Figs. 1-4 of the drawing which picture sequentiallydifferent positions or" the switch contact actuating mechanism. Fig. 1shows the switch in the on position, i. e. with the switch contactsclosed; Fig. 3 shows the switch in the off position, i. c. with theswitch contacts open; and Figs. 2 and 4 show, respec tively, thepositions of the switch actuating mechanism immediately before breaking,and immediately before making of the circuit controlled by the switchcontacts.

With reference now to the drawings, numeral 1 indicates the base plateof the switch and upon which the contact actuating mechanism is mounted.The base plate carries stationary contact elements 2, 3 which with theirmoveable counter contact elements 2a, 3a mounted on the moveable switchmechanism form the current carrying switching points which are,electrically speaking, in parallel. The switching point 2, 2a has theduty to make the circuit and the stationary contact 2 is provided withlaminated, or finger, contacts which engage practically simultaneouslythe moveable counter part 2a thereby di- 2,761,040 Patented Aug. 28,1958 ice viding the load and keeping the mechanical and thermal stressesto a minimum. The switching point 3, 3a serves as the circuit breaker;its contacts are massive block contacts which can endure a certainamount of wear caused by the cut-off arc. During one make-and-breakcycle the switching point 3, 3a will always be the last to open and thelast to close. The moveable contact 2a of the switching point 2, 2a islocated at the outer end of a single-arm lever 4 mounted pivotally at 12at its opposite end on a bracket 5 extending laterally outward from thebase plate 1. The moveable contact 30: of the switching point 3, 3a islocated on and at the outer end of one arm 6a of a bellcrank lever 6mounted pivotally at 13 intermediate its arms to the outer end of lever4. Force is applied to lever 6 by a helical compression spring 7 whichis connected at 14 to, and acts on, the other arm 6b of lever 6, theopposite end of the spring 7 being secured at 15 to bracket 5.

Arm 6b of bellcrank lever 6 is also connected at its outer end by asliding pivot connection 16 to one end of a steering arm 8, the oppositeend of arm 3 being pivotally conected at 17 to an intermediate portionof a single-arm dog-leg-shaped lever 9. One end of lever 9 is connectedpivotally at 10 to lever 4 intermediate the ends of the latter, and theopposite end of lever 9 is pivotally connected at 18 to the outer end ofa crank 11, the inner end of this crank being fixed to a shaft rotatableabout its axis 19.

The dog-lever 9 forms a knee joint with the driving crank 11 which isarranged to always rotate in the direction indicated by the arrow andwill assume a dead-center position when the switch contacts are closed,the position indicated in Fig. 1, wherein it will be seen that the crankaxis 19, crank pivot 18 and pivot 16 all lie in a straight line.

The driving crank 11 can be operated either manually, or by a motor or aspring driven device. It performs one complete revolution during onecircuit breaking and making operation.

When, for the purpose of breaking the circuit, crank 11 is set in motionin the direction indicated by the arrow, lever 9 will deflect the kneejoint, and lever will then begin to turn about its pivotal mountingpoint 12 at the bracket 5. The switching point 2, 2a then opens. Due tothe pivotal mount of the lever 4 the position of bellcrank lever 6,which is then using the switching point 3, 3a as it fulcrum, will alsochange. The spring '7 will now expand longitudinally and its pressurewill lessen. However, the contacts of the switching point 3, 3a willstill be subject to, at least, the same pressure because, due to thedisplacement of the bellcrank lever 6, the eifective leverage of thespring 7 has increased (see Figure 2). When the crank 11 continues itsturning motion the steering arm 8 will take up the pressure of thespring after the contacts 2 and 2a have reached a certain distance fromeach other and will open the switching point 3, 3a. The components ofthe switch will then take up the positions shown in Figure 3 and thespring 7 will be set again.

At the closing of the switch, which now follows, the contacts of theswitching point 2, 2a will engage first. The steering arm 8, lever 9 andthe still turning crank 11 will retard the closing of the movablecontact 3a of the switching point 3, 3a (see Figure 4) but these willultimately close as the knee of the dog-leg lever 9 rises due to furtherrotation of crank 11 causing steering arm 8 to rise which results inrotation of bellcrank lever 6 and hence movement of contact 3a intoengagement with contact 3.

In conclusion it will be understood that while I have described andillustrated one practical embodiment for the invention various changesin the construction and arrangement of parts may be made withoutdeparting from the spirit and scope of the inventive concept as definedin the appended claims.

I claim:

1. A lever actuated switching mechanism comprising two current carryingand parallel arranged sets of switching points, one of said sets ofswitching points being the last to be opened as well as the last to beclosed, the movable contact element of said set of switching points thatis last to be opened and closed being located on one arm of a bellcranklever, said bellcrank lever being subjectable to a force tending torotate the same about its pivot and said bellcrank lever being pivotallymounted at the end of a first single-arm lever, and said first singlearm-lever carrying the movable contact element of said other set ofswitching points, the other arm of said bellcrank lever having pivotallyconnected thereto one end of a steering arm, the other end of saidsteering arm being pivotally connected to an intermediate portion of asecond singlearm lever, one end of said second single-arm lever beingpivotally connected at an intermediate point on said first single-armlever and the other end of said second single arm lever being pivotallyconnected to the outer end of a crank arm rotatable always in the samedirection, said second single-arm lever forming a knee joint with saidcrank and which joint occupies a dead-center position when said sets ofswitching points are closed.

2. A lever actuated switching mechanism as defined in claim 1 whereinthe contact pressure at the set of switching points which is last to beopened and closed is effected by a spring connected between said otherarm of said bellcrank lever and a stationary point on the base plateupon which the switch actuating mechanism is mounted.

References Cited in the file of this patent UNITED STATES PATENTS2,581,181 Favre Ian. 1, 1952

